This invention relates to drilling tools and is more particularly concerned with the provision of depth stop devices in such tools.
According to the invention there is provided a drilling tool having a depth stop device comprising a depth stop rod mounted on the body of the tool for guided sliding movement along the longitudinal axis thereof in directions parallel to the direction of drilling movement, and a lever mounted on the body of the tool for pivotal movement about an axis extending normally with respect to the longitudinal direction of the rod but offset to one side of the rod, said lever being resiliently biased into a rotational position about said axis on which position a detent edge of the lever engages the rod and movement of the rod relative to the body of the tool resulting from abutment of the rod with a workpiece operates in a sense to rotate the lever in the same direction as the biasing force thereon and to urge the detent edge into tighter engagement with the rod, and said lever being movable against the biasing force of the spring to disengage the detent edge from the rod.
While the frictional grip of the detent edge on the rod is adequate for very light tools, the surface of the rod engaged by the detent edge is preferably knurled to provide substantially a mechanical lock between the two components.
In preferred arrangements according to the invention, said detent edge engages the surface of the rod remote from said axis. In one preferred construction the rod extends through an aperture in the lever, part of the edge of the lever bounding the aperture constituting said detent edge.
In some circumstances according to the invention, the lever provides a second detent edge for engaging the opposite side of the rod from that engaged by the first detent, and means is provided for permitting limited relative movement of the lever and the rod in a direction generally lengthwise of the lever.